Seventy firefighters have been tackling a "significant" blaze at the famous Camden Lock Market in north London.
London Fire Brigade said 10 fire engines were sent to the market, which is a popular tourist attraction, but the blaze is now under control although crews would work into the morning to dampen down hotspots.
It said earlier the first, second and third floors plus the roof of the building were burning.
The building contained a number of different businesses, it said.
One eyewitness said the fire was moving "very fast" and there were fears of an explosion in nearby buildings.
The Metropolitan Police said firefighters were already at the scene when its officers arrived.
"It is unknown at this stage if any persons are injured."
Witness Joan Ribes, 24, said: "I was just passing by when I saw the fire and they started to get firefighters and police, it was all very fast."
"We called the police to close the street to the traffic because it was very dangerous, the fire was flying through the air to the surrounding areas.
"The fire was moving very fast. People were watching, but we were scared the building could explode at any time since there are restaurants with kitchens nearby."
A major blaze ravaged the area in 2008, shutting the attraction for several months.
It houses more than 1000 sellers, street food traders and independent stores.
The markets are open every day from 10am till late.
- BBC / Reuters